Patent GB-798749-A (GB)
Title: Improvements in or relating to automatic telephone exchanges providing automatic transfer service
IPC: H04Q3/00
Filed: 1955-03-28
Abstract: 798,749. Automatic exchange systems. TELEFONAKTIEBOLAGET L. M. ERICSSON. March 28, 1955 [March 27, 1954], No. 9055/55. Class 40 (4). In a cross-bar exchange with central arrangements for recording messages and automatically answering calls and with arrangements for diverting calls, a special service is made available automatically on dialling an appropriate prefix. By dialling a prefix 09 at station Al (No. 11, Fig. 1), followed by the number 12 of station A2, all subsequent calls for A2 are diverted to A1. By dialling 02 and replacing the receiver at A1 subsequent calls to A1 are diverted to a machine T1 which reproduces a predetermined announcement. On dialling 00 at A1 a message can be recorded on a machine T2, the message being reproduced once for checking before the receiver is replaced at A1. Subsequent calls to A1 are diverted to T2 which reproduces the recorded message. A main register REG records only the dialled number and seizes an auxiliary register RO in response to the first digit 0 of a prefix. The auxiliary register records the number of the calling line and of the line or equipment to which calls are to be routed. The auxiliary - register remains set when the main register REG restores. A marker M and the registers REG, RO are interconnected by a multiple U so that auxiliary register RO may subsequently recognise the registration of a number to be diverted and takes over control of the marker M from the register REG. A further prefix O1 is dialled to cancel a transfer order. Call from A1 (No. 11) to A2 (No. 12). Normal service. When the receiver is lifted, line relay LR1, Fig. 3, pulls up and is then held in series with select magnet S11 in register finder RS, Fig. 4. Magnet S 11 is allotted to a group of ten lines. A free register REG is seized as relay RR4 pulls up therein in series with relay H3 in a selecting chain H1, H2, H3. Relays D2, RR2 and operating magnet GB1 of RS follow relay RR4 which is now de-energized. The looped line L is extended over leads r1, r2 to operate relay RR1 which is followed by relay RR3 to hold GB1 and RR2 before RR4 falls back. Dialling tone is transmitted by SU2 in the register over the lower winding of RR1. Dialled impulses are repeated by RR 1 , counted in known manner by a relay set PR and registered in relay sets E1-E0 (tens) E11-E10 (units). The first digit 1 operates relay E1 and ER1 cuts off dialling tone. The second digit 2 operates E12 with ER2 and, if the marker M is free, it is seized as relay RR8 and chain relay G3 pull up in series. Slow relay MR4 is energized, but does not operate unless the line tests busy later. Relay D1 follows RR8 and marks the calling line in the multiple t, relays T11, T1 pulling up to mark the calling line on multiple p. The register operates relays U11, U2 to mark the called line on multiple p. Each link SN can be used to interconnect any two lines. A free link SN is selected by a relay chain H11-H10, the link shown being selected by operation of select magnet S9 of switch BL1, and relays H11, MR2 in series over wires d, m2, g3. When MR2 pulls up the called line is tested by relay MR3 in a circuit over wire v2, wire p12 marking the called line in multiple p to magnet B2. If the line is free, MR3 pulls up and magnet B2 follows only when MR3 short circuits its own. high resistance winding. With MR3 up, the calling line magnet B1 operates over wires v1 and p11 (marked by T11, T1). The line relay LR1 is now held by ground through parallel windings of relays N2, N3 in the link SN and both operating magnets B1, B2 are held over wire c and a contact of N2. Ringing current from generator RG in SN is transmitted over lead b to station A2 and ringing tone from SU3 is transformed by windings of N2 and fed over wire c to the calling station A1. The register was released when magnet B1 disconnected relay RR1 from the line L1. Before A2 replies, the circuit is held by M, line relay LR1 and relay N2 being energized in series. When A2 replies, slow-acting relay N1 pulls up as a direct current is superimposed on the ringing current. Relays LR1, and N3 fall back and N2 falls back slowly. When relay N2 is back N3 pulls up again and the connection is held by N3 until both stations release, N1 being held meantime over its lower winding. Transfer of calls from A2 to A1. The prefix 09 is dialled at A1 and is registered by relays E0 and E19. Relay RR7 following E0 causes a free relay set or auxiliary register RO to be selected by a chain R, the relay set being seized as relays RO2, RO4 pull up with R1. Relay RR5, following E19, returns the register to normal, except for relays RR3, RR7, but the register is held in readiness for a further registration. When dialling tone is heard at A1, the number 12 is dialled and registered by relays E1, E12. The number 11 of the calling line is marked on multiple t and is registered on relay set RO by relays K11, K21. The called number 12, marked on multiple u, is registered by relays K31, K42. The corresponding register markings on multiple pare ineffective in the absence of marking potentials on wires V1, V2. Relay RR5 pulls up again over its upper winding and wire g5, the register is restored to normal a second time, relay RO7 pulls up and dialling tone is again transmitted. The hand-set is restored at A1 and the register is released. If the number 12 is dialled in another call, the markings on multiple u energize both the upper and the intermediate windings of RO8 which operates only when these two windings are energized. Relay MR1 follows making RO effective instead of the register REG to mark the wanted line on multiples u and p. The number marked is 11, registered on relays K11, K21. The connection is completed as before. Cancellation of transfer order. The prefix O1 followed by the number 12, dialled from any station is sufficient to stop the transfer of calls for station number 11 to number 12. Relay RR6 pulls up in the register in response to the registration of the units digit 1 on E11. When relay RO8 in the relay set RO responds to the number 12, release relay RO3 pulls up over wire g6 and the relay set is restored to normal. Reproducing machine used to answer calls. If the prefix 02 is dialled at A1, it is registered by relays EO, E12 and as relay RR5 is not operated by units digit 2 to cancel the registration, the digits 02 are also registered by relays K30, K42 in RO without further dialling. Relay RR5 is now operated by the auxiliary register RO over wire g5 and the register REG returns to normal. Dialling tone is transmitted and the hand-set is replaced at A1. The calling number 11 is registered as before on relays K 11, K21. As relay RO7 is disabled by K30 registering the first digit 0 of the prefix, subsequent calls to number 11 are re-routed to O2 which is the number of the reproducing machine T1. Recording of message and subsequent reproduction when called. The prefix 00 is dialled and registered by relays EO, E10. The marker is seized by operation of relays RR8, G3 and with relay RR7 following EO, the calling and the called numbers (11, 00) are registered by relays K11, K21 and K30, K40. During the operating time of relay RO1 which energizes in series with the relays of RO, a free recording and reproducing machine T2 is selected by a relay chain F. In the case of T2, relays F0, F1 pull up followed by RO1, RO6, RO8 (lower winding) and MR1. The auxiliary register RO marks the calling and called lines over multiple p and the connection is completed as before, relay MR2 being operated over contacts of FO, F1. The machine T2 and an amplifier TF2 are started by relays TFR when the c contacts are closed in switch BL4. After a burst of dialling tone there are 30 secs. for recording a message. Relay FR2 is then operated by the machine which is reversed so that the message is reproduced for checking. The hand-set is replaced at A1 and subsequent calls thereto are routed to the machine which reproduces the recorded message. Called number busy. If the called number is busy, test relay MR3 allows MR4 to pull up. Relay MR5 follows in series with select magnet SO which connects busy tone from SU1 to the calling line. Specification 634,706 is referred to.